Water heating and storage system with mixing valve

ABSTRACT

The invention relates to a water heating system in which a single water heater is utilized in combination with a storage tank and pump to provide hot water for various uses. The invention is particularly directed to the use of a thermostatic mixing valve set at a predetermined temperature and located at a juncture between a recirculating conduit from the water heater and the conduit for the flow of water from the storage tank or a source of fresh water supply to the water heater so that water which has already been heated by the water heater may be mixed with the colder water supplied to the water heater to be heated.

United States Patent Duncan [54] WATER HEATING AND STORAGE SYSTEM WITHMIXING VALVE [72] lnventor: Angelo N. Duncan, Bourbonnais, Ill.

[73] Assignee: A. 0. Smith Corporation, Milwau- [58] Field of Search..l26/362; 237/8 R, 8 C, 19,

[ Dec. 12,1972

3,413,969 12/1968 Whittell, Jr ..126/362 Primary Examiner-Charles .l.Myhre Attorney-Andrus, Sceales, Starke & Sawall [57 ABSTRACT Theinvention relates to a water heating system in which a single waterheater is utilized in combination with a storage tank and pump toprovide hot water for various uses. The invention is particularlydirected to the use of a thermostatic mixing valve set at apredetermined temperature and located at a juncture between arecirculating conduit from the water heater 237/63 and the conduit forthe flow of water from the storage tank or a source of fresh watersupply to the water [56] keferencgs Clad heater so that water which hasalready been heated by UNITED STATES PATENTS the water heater may bemixed with the colder water supplied to the water heater to be heated.2,245,967 6/l94l Dillon ..l26l362 3,397,841 8/1968 Kieslich ..237/8 4Claims, 3 Drawing Figures l J 4 a /i l I a I Y I i 1 g= I I I A! k I 20Z/ /a PATENTEDUEC 12 m2 FIGJ N FIG- 3 FIG- 2 INVENTOR. ANGELO N. DUNCANf4 IMAM Attorneys WATER HEATING AND STORAGE SYSTEM WITH MIXING VALVEBACKGROUND OF THE INVENTION In previously known water heating systemswhich employ a separate heater for heating water to be stored in astorage tank at a predetermined temperature, a substantial period oftime passes before the water heated by the heater reaches the desiredtemperature. 0

SUMMARY OF THE INVENTION The invention overcomes the previously knownproblems by providing a construction wherein the heater operates with asmall rise in temperature to furnish water at the temperature desiredwithin a short space of time. The construction permits a stabletemperature rise in the heater despite changes in temperature of theincoming supply water whether from the storage tank or other source ofsupply.

The results obtained are provided by a recirculating conduit connectedto the outlet conduit of the heater which recirculates water from theoutlet conduit heater to the inlet conduit of the heater by operation ofa pump in the system through a thermostatic mixing valve. The valvemixes the colder inlet water from the inlet conduit with therecirculated hot water and the mixed water then flows into the heater.The colder water provided to the mixing valve comes either from thestorage tank or a fresh water supply.

In the operation at start up of the system, the thermostat of the mixingvalve is set at a predetermined temperature and normally the cold inletside of the mixing valve will be closed and the hot inlet side will beopen and the water in the system will be circulated by the pump onlythrough a mixing loop consisting of the inlet conduit, the heater, theheater outlet, the recirculating conduit and thence through the mixingvalve and inlet conduit back to the heater. When the water hasrecirculated through the mixing loop a few times, the temperature of thewater will rise causing the thermostat to open at its predeterminedtemperature setting and permitting the cold water to enter the valve andmix with the hot water. When this occurs, a portion of the water fromthe heater will continue to recirculate through the mixing loop and asecond portion will flow to the storage tank or be discharged from thesystem for use.

The drawings provided herewith illustrate the best mode of the inventionpresently contemplated by the inventor.

In the drawing:

FIG. 1 is a schematic representation of the water heating system of theinvention;

FIG. 2 is a cross sectional view of a mixing valve connected into thesystem which may be employed with the invention; and

FIG. 3 is a wiring diagram of the system of FIG. 1.

The water heater system with which the invention is illustrated has ahot water storage tank 1 which stores water at a predeterminedtemperature, such as lF., and is connected to a gas fired water heater 2by the heater inlet conduit 3. The water which is heated by water heater2 is circulated from the water heater 2 through the outlet conduit 4 tothe upper portion of water storage tank 1 or to the discharge conduit 5which may be connected to outlet conduit 4 for withdrawal of hot water.A separate discharge conduit, not shown, corresponding to conduit 5 maybe connected to the water heater 2 rather than to the outlet conduit 4to withdraw hot water from the system.

Thewater is circulated through the closed system described, by pump 6which is shown as located in inlet conduit 3 adjacent the water heater2. Fresh water is supplied to the inlet conduit 3 through supply conduit7 when water is withdrawn from the system. inlet conduit 3 may be closedby valve 8 and similarly, outlet conduit 4 may be closed by valve 9. Anadjustable flow cock 10 may be provided in inlet conduit 3 to adjust theflow rate of the water through the water heater 2.

The hot water heater 2 may be of the conventional type having coilsthrough which the water flows and which is heated by a gas burner 11.Gas is provided to the burner 11 through a gas line 12 and the flow ofgas through the line is controlled by gas valve 13 which may havesensors to sense the temperature of the water flowing through heater 2to actuate mechanism, not shown, to reduce gas flow or modulate the gasflow as the desired temperature in the system is approached. Asillustrated in the drawings, however, operation of valve 13 is under thecontrol of a temperature control 14 which is secured to the wall of tank1 and senses the temperature of the water in tank I, to open or closevalve 13.

Limit control thermostat 15 is disposed in the coils of water heater 2and responds to the water temperature therein to open electricalcontacts when a predetermined temperature has been reached to deactivatethe electrical circuit resulting in the closing of the valve 13 andstopping the flow of gas to burner 11.

The electrical circuit of the system is illustrated in FIG. 3. When thetemperature of the water in tank I drops below a temperature such as F.,control 14 of tank 1 actuates the pump 6 to circulate water through thesystem and supplies power to the input terminals of the gas valve 13 tocondition the circuit so that if limit control 15 on the heater isclosed, valve 13 will open to deliver gas to burner 11. In the eventthat.

the temperature of water heater 2 exceeds a predetermined amount, suchas 200 F., limit control 15 will open and this deactivates valve 13, butpump 6 will continue to circulate water in the system as long as controlI4 is closed. However, when the temperature of the water in the tank 1exceeds a temperature such as 185 F., then control 14 on tank 1 opensand the pump 6 stops if it is still in operation and, likewise, shouldthe valve 13 be open, the power would be cut off and valve 13 wouldclose. The controls 14 and 15 may be set for any desired temperaturecontrol other than those given in the example of the operation of thesystem.

In order to stabilize the operation of water heater 2 with respect tothe temperature rise of the water heated therein and to provide usablehot water within a faster time limit, the system is provided with therecirculating conduit 16 for recirculating heated water from the heaterback through inlet line 3. Conduit 16 is connected at one end to tee 17which connects the outlet conduit 4 to the water heater 2 and to thetank 1. At the opposite end, conduit 16 is connected to the mixing valve18 which is connected to inlet conduit 3.

Mixing valve 18 is of a conventional type and, as shown in FIG. 2, has abody 19 having a cold water inlet port 20 connected to inlet conduit 3for passage of water from the tank 1 or supply conduit 7. Opposite port20 is a second inlet port 21 for passage of hot water from recirculatingconduit 16. The discharge port 22 of valve 18 also connects with inletconduit 3.

The flow through the mixing valve 18 is controlled by the setting of thethermostat 23 which, through stem 24, actuates valve member 25. Thevalve member 25 is normally biased by spring 26 against upper seat 27 sothat only hot water would flow through the valve, but may be moved bythe thermostat 23 to rest on lower seat 28, or may be regulated bythermostat 23 to varying positions between the seats 27 and 28 to effectmixing of the recirculated hot water with the incoming colder water ofthe inlet line 3 in accordance with the setting of thermostat 23.

Referring now to the operation of the recirculating branch of the systemand mixing valve 18, when the system starts up by actuation of pump 6and the opening of valve 13 by closing of the control 14 on tank 1 tosupply power to the circuit, the valve member 25 is resting on upperseat 27 so that inlet port 20 for colder water is closed, and only hotwater flows through the port 21 and through the valve to the branch ofinlet conduit 3 leading to water heater 2. The water is thus circulatedby pump 6 in the loop consisting of the branch of inlet conduit 3leading from the mixing valve 18 to water heater 2, through water heater2, thence through the branch of outlet conduit 4 leading from waterheater 2 to tee 17 and thence through recirculating conduit 16 andmixing valve 18 and then back to the water heater 2 through inletconduit 3.

The operation of the system can be illustrated by the following example:

Desired outlet temperature of water drawn from storage tank l85F. lnlettemperature of city water 50F. Temperature rise of water flowing throughwater heater 45F. Mixing valve setting 140F Temperature use in system135F.

Under the design conditions set forth in the example, when the water iscirculated through the heater it would normally be raised in temperature45F., thus circulation through the heater three times would give a totalincrease in the temperature of the water of 3 X 45F., or l3SF., whichwould be added to the inlet temperature of the water of 50F. to providethe outlet temperature of 185F. However, due to heat losses in theconduits it has been found necessary to circulate the water 3 v2 totimes through the heater to obtain the 135F. temperature rise in thesystem.

When the water flowing through the mixing valve 18 exceeds 140F. as setforth in the above example, then the valve member 25 will be opened bythermostat 23 and colder water will flow into mixing valve 18 throughport and mix with the hot water recirculating from the heater for flowto the heater. When this occurs under the design conditions of the aboveexample, twothirds of the water flowing through water heater 2 initiallyrecirculates through valve 18 and this would continue until the hotwater reaches the bottom of tank 1. When this occurs mixing valve 18adjusts the hot water inlet port 21 to reduce the circulated flowthrough conduit 16, and when the temperature of the water in the bottomof tank 1 increases above l40F. port 21 is closed and no recirculatedwater would flow through valve 18, and thus only water flowing inconduit 3 from the storage tank 1 would pass to the heater. At any time,however, that water is withdrawn from the system, fresh water would besupplied through supply conduit 7.

Thus, under the water recirculating system of the invention, waterheater 2 operates with only a small rise in temperature and yet water issupplied therefrom at a usable temperature without too much time passingbefore the desired temperature of the water in the storage tank 1 isobtained.

Although the invention has been illustrated in connection with a gaswater heater and electric controls, it is contemplated that the waterheater may be heated by other means such as electrically or by oil orindirectly, and the heater could be of the tank type. Furthermore,controls other than electrical may be employed in the system.

Various modes of carrying out the invention are con templated as beingwithin the scope of the following claims particularly pointing out anddistinctly claiming the subject matter which is regarded as theinvention.

I claim:

1. In a hot water heating system including a hot water storage tank anda water heater, a water heater circuit for circulation of water from thestorage tank through an inlet conduit and the water heater and back tothe storage tank through an outlet conduit from the water heater tomaintain water in the storage tank at a predetermined temperature, arecirculating conduit connected in the circuit between the inlet andoutlet conduits for recirculation of at least a portion of the waterdischarged from the water heater back through the water heater, a mixingvalve disposed in the water heater circuit at the juncture of the inletand recirculating conduits and being adapted under a predeterminedtemperature setting to mix the recirculating hot water with colder waterflowing in the inlet conduit, pump means disposed in the water heatercircuit for effecting upon actuation circulation of the water throughthe circuit, heating means to heat the water in the water heater, andcontrol means disposed in the water heater circuit to regulate theheating means and the temperature of the water supplied to the storagetank by the water heater.

2. The hot water heating system of claim 1, and a fresh water supplyconduit connected to the inlet conduit, and a discharge conduitconnected in the water heater circuit for withdrawal of hot water.

3. The hot water heating system of claim 1, in which the pump means islocated in the inlet conduit between the mixing valve and the waterheater.

4. The hot water heating system of claim 1, and a thermostat in themixing valve for opening and closing passages through the valve for flowof either hot or cold water or actuating the valve to a position wherethe colder inlet water mixes with the hot water recirculated through theheater.

1. In a hot water heating system including a hot water storage tank anda water heater, a water heater circuit for circulation of water from thestorage tank through an inlet conduit and the water heater and back tothe storage tank through an outlet conduit from the water heater tomaintain water in the storage tank at a predetermined temperature, arecirculating conduit connected in the circuit between the inlet andoutlet conduits for recirculation of at least a portion of the waterdischarged from the water heater back through the water heater, a mixingvalve disposed in the water heater circuit at the juncture of the inletand recirculating conduits and being adapted under a predeterminedtemperature setting to mix the recirculating hot water with colder waterflowing in the inlet conduit, pump means disposed in the water heatercircuit for effecting upon actuation circulation of the water throughthe circuit, heating means to heat the water in the water heater, andcontrol means disposed in the water heater circuit to regulate theheating means and the temperature of the water supplied to the storagetank by the water heater.
 2. The hot water heating system of claim 1,and a fresh water supply conduit connected to the inlet conduit, and adischarge conduit connected in the water heater circuit for withdrawalof hot water.
 3. The hot water heating system of claim 1, in which thepump means is located in the inlet conduit between the mixing valve andthe water heater.
 4. The hot water heating system of claim 1, and athermostat in the mixing valve for opening and closing passages throughthe valve for flow of either hot or cold water or actuating the valve toa position where the colder inlet water mixes with the hot waterrecirculated through the heater.